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  2. Emergency light - Wikipedia

    en.wikipedia.org/wiki/Emergency_light

    Some lights are halogen, and provide a light source and intensity similar to that of an automobile headlight. Early battery backup systems were huge, dwarfing the size of the lights for which they provided power. The systems normally used lead acid batteries to store a full 120 VDC charge.

  3. Emergency power system - Wikipedia

    en.wikipedia.org/wiki/Emergency_power_system

    For a 208 VAC emergency supply system, a central battery system with automatic controls, located in the power station building, is used to avoid long electric supply wires. This central battery system consists of lead-acid battery cell units to make up a 12 or 24 VDC system as well as stand-by cells, each with its own battery charging unit ...

  4. Uninterruptible power supply - Wikipedia

    en.wikipedia.org/wiki/Uninterruptible_power_supply

    The difference between the two voltages is because charging a battery requires a delta voltage (up to 13–14 V for charging a 12 V battery). Furthermore, it is easier to do the switching on the line-voltage side of the transformer because of the lower currents on that side.

  5. Command-line argument parsing - Wikipedia

    en.wikipedia.org/wiki/Command-line_argument_parsing

    PHP uses argc as a count of arguments and argv as an array containing the values of the arguments. [ 4 ] [ 5 ] To create an array from command-line arguments in the -foo:bar format, the following might be used:

  6. Backup battery - Wikipedia

    en.wikipedia.org/wiki/Backup_battery

    A valve-regulated lead-acid battery is a battery type that is popular in telecommunications network environments as a reliable backup power source. VRLA batteries are used in the outside plant at locations such as Controlled Environmental Vaults (CEVs), Electronic Equipment Enclosures (EEEs), and huts, and in uncontrolled structures such as ...

  7. Extra-low voltage - Wikipedia

    en.wikipedia.org/wiki/Extra-low_voltage

    Some types of landscape lighting use SELV / PELV (extra-low voltage) systems. Modern battery operated hand tools fall in the SELV category. In more arduous conditions, 25 V RMS alternating current or 60 V (ripple-free) DC can be specified to further reduce hazard. Lower voltage can apply in wet or conductive conditions where there is even ...

  8. Electrical ballast - Wikipedia

    en.wikipedia.org/wiki/Electrical_ballast

    It can be incorporated into an existing fluorescent light fixture or mounted remotely outside of it. When power is lost, the ballast will illuminate one or more lamps in the fixture at a reduced output for a minimum of 90 minutes (as required by code). These can be used as an alternative to egress lighting powered by a back-up electrical generator.

  9. VRLA battery - Wikipedia

    en.wikipedia.org/wiki/VRLA_battery

    A 12V VRLA battery, typically used in small uninterruptible power supplies and emergency lamps.. A valve regulated leadā€acid (VRLA) battery, commonly known as a sealed lead-acid (SLA) battery, [1] is a type of lead-acid battery characterized by a limited amount of electrolyte ("starved" electrolyte) absorbed in a plate separator or formed into a gel, proportioning of the negative and ...